Samyo 6 Inch / 150mm Optical Glass Triangular Prism Triple Prism for Photography Effects Physics Teaching Light Spectrum Optics Kits Break light up into its spectral components(the colors of the rainbow). Offer good reflections and color seperation. Show your kids a rainbow. Material: optical glass, not plastic. Side Length: 1.17 inch / 3cm. Prism Length: 6 inch / 15cm.